<?xml version="1.0" encoding="utf-8"?>
  
  <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns="*" creationComplete="iFrame.visible=true">
  
      <mx:HBox width="100%" height="100%">
  
          <mx:Panel title="Tree" width="200" height="100%" roundedBottomCorners="true">
               <mx:Tree id="tree" width="100%" height="100%" dataProvider="{treeData}"
                       labelField="@label" showRoot="false"
                       change="iFrame.source = (Tree(event.target).selectedItem.attribute('path').toString());"  />
          </mx:Panel>
  
          <mx:Panel width="100%" height="100%" title="Content" paddingTop="1" paddingBottom="1" paddingLeft="1" paddingRight="1" >
              <IFrame id="iFrame" source="http://www.adobe.com/devnet/flex/" width="100%" height="100%"  />
              <mx:ControlBar>
                  <mx:CheckBox id="cbVisible" label="IFrame Visible" selected="true" click="iFrame.visible=cbVisible.selected"/>
              </mx:ControlBar>
          </mx:Panel>
  
      </mx:HBox>
  
      <mx:XMLList id="treeData">
          <node label="Flex Resources">
              <node label="Flex Developer Center" path="http://www.adobe.com/devnet/flex/" />
              <node label="Flex Team Blog" path="http://weblogs.macromedia.com/flexteam/" />
              <node label="Flex Blogs on MXNA" path="http://weblogs.macromedia.com/mxna/FeedList.cfm#Flex" />
              <!-- these sites pop themselves out of a frame:
              <node label="flex.org" path="http://www.flex.org" />
              <node label="Adobe Labs" path="http://labs.adobe.com/wiki/index.php/Main_Page" />
              -->
          </node>
          <node label="Search">
              <node label="Google" path="http://www.google.com" />
              <node label="Yahoo" path="http://www.yahoo.com" />
          </node>
      </mx:XMLList>
  
  </mx:Application>